Hydrophobic sand (or magic sand) is a

toy A toy or plaything is an object that is used primarily to provide entertainment. Simple examples include toy blocks, board games, and dolls. Toys are often designed for use by children, although many are designed specifically for adults and p ...

made from

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

coated with a

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

compound. The presence of the hydrophobic compound causes the grains of sand to adhere to one another and form

cylinder A cylinder () has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite ...

s (to minimize

surface area The surface area (symbol ''A'') of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the d ...

) when exposed to water, and form a pocket of air around the sand. The pocket of air makes magic sand unable to get wet. A variation of this, kinetic sand, has several of the same properties, but acts like wet sand that will not dry out. Hydrophobic sand, whether the wet or dry type, will not mix with water.

History

The earliest reference to waterproof sand is in the 1915 book ''The Boy Mechanic Book 2'' published by ''

Popular Mechanics ''Popular Mechanics'' (often abbreviated as ''PM'' or ''PopMech'') is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do it yourself, and technology topics. Military topics, aviation an ...

''. The Boy Mechanic states waterproof sand was invented by East Indian

magicians Magician or The Magician may refer to: Performers * A practitioner of magic (supernatural) * A practitioner of magic (illusion) * Magician (fantasy), a character in a fictional fantasy context Entertainment Books * ''The Magician'', an 18th-ce ...

. The sand was made by mixing heated sand with melted

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give lo ...

. The wax would repel water when the sand was exposed to water. Magic sand was originally developed to trap ocean

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s near the shore. This was done by sprinkling magic sand on floating petroleum, which would then mix with the oil and make it heavy enough to sink. Due to the expense of production, however, it is no longer used for this purpose. Hydrophobic sand has also been tested by utility companies in Arctic regions as a foundation for

junction box An electrical junction box (also known as a "jbox") is an enclosure housing electrical connections. Junction boxes protect the electrical connections from the weather, as well as protecting people from accidental electric shocks. Functions of ...

es, as it never freezes. It is also used as an aerating medium for potted plants.

Properties

Magic sand

The properties of Magic sand are achieved using ordinary beach sand, which contains tiny particles of pure

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

, and exposing it to vapors of

trimethylsilanol Trimethylsilanol (TMS) is an organosilicon compound with the formula . The Si centre bears three methyl groups and one hydroxyl group. It is a colourless volatile liquid.Paul D. Lickiss: ''The Synthesis and Structure of Organosilanols'', Advances i ...

( CH₃)₃ Si OH, an

organosilicon Organosilicon chemistry is the study of organometallic compounds containing carbon–silicon bonds, to which they are called organosilicon compounds. Most organosilicon compounds are similar to the ordinary organic compounds, being colourless, f ...

compound. Upon exposure, the trimethylsilanol compound bonds to the silica particles while forming water. The exteriors of the sand grains are thus coated with

groups. When Magic sand is removed from water, it is completely dry and free-flowing.

Brands

;Kinetic Sand * A toy trademarked and produced by

Spin Master Spin Master Corp. (formerly known as Spin Master Toys) is a Canadian multinational toy and entertainment company. Spin Master employs over 1,600 people globally with offices in Australia, Canada, China, France, Germany, Hong Kong, India, Ital ...

. Kinetic Sand looks like regular wet sand but is available in different colors. It can be molded into any desired shape. It is 98% ultra-fine grain sand mixed with 2% dimethicone (

polydimethylsiloxane Polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone, is a silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication and passive daytime radiative cooling. PDMS is particularly known for its ...

), and coated with olive oil. Because of its oil coating, the sand never dries out. It mimics the physical properties of wet sand.Kinetic Sand information
WebPage; Chymist; PDF format. ;Aqua Sand * Similar properties as above.

References

External links

acs.org
Magic Sand experiment from the American Chemical Society
youtube.com
Video of how to make Magic Sand {{DEFAULTSORT:sand, hydrophobic Wham-O brands Chemistry classroom experiments Water toys Educational toys Construction toys Sand Sensory toys Office toys